Nutritional value, fermentation kinetics and estimated milk yield of corn silages cut at different heights

Abstract

The dry matter production DM (ton ha-1), nutritional value, estimated milk yield and fermentation kinetics of corn silage cut at 20, 40 and 60 cm over the soil surface were evaluated. The corn hybrid PIONEER 33G66 was planted at a density of 125,000 seeds ha^-1, with a row distance of 0.80 m, and harvested at half milk line (115 d of age), and ensiled in laboratory mini silos of 5 kg (n=3). After 45 d, the silos were opened and analyzed by triplicate for pH, DM, OM, Ash, CP, EE, NDF, ADF, ADL, in vitro DM and NDF digestibility (IVDMD and IVNDFD), and fermentation kinetics. Milk yield and NEL were estimated
using the MILK2000 model. Data were analyzed using PROC GLM of SAS, adjusting a model in which height of cut was the fixed effect. Production of DM ha^-1 decreased by 12.7% by rising cutting height to 60 cm. The NDF and CP concentration were linearly reduced (P < 0.05). NEL tended (P < 0.07) to improve when the height of cutting was raised from 20 to 60 cm (1.2 vs 1.4 Mcal kg^-1 DM). Estimated milk yield was not different among treatments. The asymptotic gas production was increased (P < 0.05) by rising cutting height to 60 cm; the gas production rate at 72 h was higher (P < 0.05) in corn silage
cut at 60 cm. The fermentation parameter B was decreased linearly (P < 0.05) by rising cutting height. The parameter C was high in corn silage cut at 20 cm vs corn silage cut at 40 and 60 cm.